This invention relates to wick fed liquid fuel-burning systems such as kerosene heaters. More particularly this invention relates to an apparatus for limiting the spread of excessive flames by extinguishing the flame of a wick fed liquid fuel-burning apparatus in response to sensing excessive heat. The apparatus extinguishes the flame by retracting the wick which smothers the flame and shutting off the flow of liquid fuel from the fuel tank which precludes additional fuel from reaching the flames.
In wick fed liquid fuel-burning heaters the flame is provided liquid fuel for combustion by a wick which is exposed to the oxygen of the atmosphere. Once the wick has been ignited, flame intensity and heat generation are controlled by positioning the wick with respect to a wick receiving chamber. The greater the amount of wick that is exposed, the greater is the flame intensity and heat.
One foreseeable hazard in using wick fed liquid fuel-burning heaters is the possibility of a fire resulting from excessive flames due to a flare-up. Flare-ups occur for a number of reasons, including using an inappropriate fuel, such as gasoline in a kerosene heater; using contaminated fuel or when a freestanding heater is tipped over and fuel escapes out of the wick supply reservoir. Once fuel escapes outside of the wick supply reservoir, due to "over-wicking" by using a more volatile fuel than kerosene, or due to tip over spills or due to other reasons, the possibility of a fire drastically increases.
The prior art includes "tip over" safety devices and several patents reflect efforts to incorporate certain safety features in fuel burning heaters. Examples include U.S. Pat. Nos. 4,424,019 issued Jan. 3, 1984 to Nakamura and 4,562,825 issued Jan. 7, 1986 to Nishikawa. However, these examples of liquid fuel-burning heaters are not provided with heat sensing devices to cause the flow of fuel to be blocked or the wick to be withdrawn.
Accordingly, an object of the present invention is to limit the spread of excessive flames in liquid fuel-burning heaters regardless of the cause of the excessive flames. In accordance with the present invention, means are provided for cutting off the flow of fuel to the wick supply reservoir in response to excessive heat. In the presence of excessive heat generated by unwanted flames a sensor device blocks fuel flow through a valve located between the fuel tank and the wick supply reservoir thereby shutting off the flow of fuel to the wick supply reservoir. Additionally, the present invention provides means for automatically withdrawing the wick into the wick chamber when sensing excessive heat. Thus, excessive heat activates a heat sensor which operates a lever attached to a spring loaded ratchet control gear. The lever disengages the control gear causing it to rotate. As the ratchet control gear rotates, the wick is withdrawn into the wick chamber. Once the wick is sufficiently contained within the wick chamber, it ceases to provide fuel for further combustion outside the chamber and combustion within the wick chamber cannot occur because the oxygen necessary to sustain such combustion is not available.